574 MEMOIKS OF THE NATI02sAL ACADEMY OP SCIENCES. 



V 



Plate LVI. 



(Stage XII.) 



Figs. 234-235. Serial transverse sections through the first larva, continued from Plate L V. x 73. 



REFERENCE LETTERS. 



Ab. V, fifth abdominal appendage. 



a.i.a., inferior abdomiuiil aorta. 



a. op., ophthalmic artery. 



a. s. a., superior abdominal artery. 



hg,, branchio.stegite. 



ftr., branchia of ambulatory appendage. 



B. t>., blood sinns. 



gg. ' ^, middle, ventral, and dorsal lobules of posterior lobe of midgat. 



H., heart. 



hg., hiiidgut. 



hij., hypodermis. 



?c. th.-ab., longitudinal commissures uniting last thoracic with first abdominal ganglia. 



Mg., midgut. 



Mg. '', lateral lobe of nudgut. 



Mg. ^, posterior lobe of midgut. 



J/«., masticatory stomach. 



Mil. e., extensor muscles of abdouiou. 



Mii.f., flexor muscles of abdomen. 



Mxiid. I-III, lir.st to third maxillipeds. 



pleu., pleurou. 



pt., pericardial sinus. 



Th. I-V, first to tilth ambulatory limb. 



